How is creating a popular a novel any different than creating a popular object? Hundreds of hours of labor go into both and the creators are entitled to the full value of said labor.
Say you have an amazing story about the vacation you took last year, and told all your friends about it. You would justifiably be pissed if you later found out one of your friends was telling that story as if they had done it. It’s the same for someone who writes a book or any other form of media.